Particulate rubbers which may be grafted or ungrafted are frequently used as elastomer components for toughening thermoplastics or other plastics. Such rubbers are usually prepared in aqueous systems, for example by emulsion or suspension polymerization. The particles formed in the suspension polymerization or precipitated in the emulsion polymerization (for example by adding a coagulating precipitating agent) are as a rule washed with water and dewatered by a suitable dewatering method, such as sieving, pressing out, filtration, decanting, settling out, centrifuging or partial thermal drying, for example by means of a pneumatic dryer. Partial dewatering by spray drying is also possible. Partially dewatered products are obtained in every case.